The Invisible Institute supports a number of projects related to public policy, including the Citizens Police Data Project (CPDP). The CPDP is a collaboration with University of Chicago Law School (specifically, the latter’s Mandel Legal Aid Clinic). Released in Nov 2015, the database contains around 56K “misconduct complaint” records for the Chicago Police force, which consists of over 8,500 officers. The data is compiled from four datasets that the CPD (Chicago Police Department) itself has provided. The timeline is 2001 to 2015, minus 2009-2010.
There are instructions on the CPDB site that explains how you can use FOIA (Freedom of Information Act) to request aditional details of allegations of interest.